Synthetic polymeric fibers have been used to make a variety of products, including carpets, drapery material, upholstery, and clothing. Often, however, such fibers (and the resulting products) have suffered from an inherent lack of water and oil repellency. Since fluorochemical groups are characteristically hydrophobic and oleophobic, various fluorochemicals have been developed for application to the polymeric fibers to impart water and oil repellency (as well as soil resistance) thereto. These fluorochemicals have most often been applied topically (for example, by spraying, padding, or finish bath immersion), but some fluorochemicals have also been useful as polymer melt additives.
In order for a fluorochemical to have utility as a polymer melt additive, it must be sufficiently thermally stable and non-volatile to withstand typical melt processing conditions. It must also be compatible with the polymer at the melt processing temperatures (to enable blending) and should preferably be able to migrate to the polymer surface as the temperature is lowered, so as to minimize the amount of fluorochemical needed to modify surface properties. This preference for migration capability has tended to limit the size of the fluorochemical molecule that can be utilized, effectively eliminating high molecular weight polymeric fluorochemicals from consideration.
Since some synthetic polymers such as polyesters require extremely high melt processing temperatures (for example, in the range of about 250-300° C.), it has been difficult to find fluorochemicals that are not only compatible with such polymers and capable of migration within them, but that are also sufficiently thermally stable. Although useful topical fluorochemical treatments have been developed, such treatments have often lacked the durability needed for some applications (for example, clothing, carpets, and upholstery), have tended to provide uneven or non-uniform coverage, and have often involved the use of environmentally unfriendly solvents. Even if water-based topical treatments are utilized, expenses are incurred for the purchase and maintenance of coating equipment.
Thus, there remains a need in the art for fluorochemicals that can successfully function as melt additives for high-melting polymers such as polyesters